Building a porch to stop draughts

However well you manage to draught seal your house with those little bits of nailed-on plastic, cold air is still going to come through the front door whenever it is opened. The only way to solve this is to build a porch large enough to allow you to shut the outside door before opening the inside one, thus preventing gusts of cold air blowing straight into the house. Before considering the design of a porch it is worth looking at the way you use the building. Typically houses have always been provided with a front door and a back door and in a terraced house both of these are usually necessary. In a semi-detached or detached house it would be possible to use only one door: this would be best covered with a generous porch, then you could brick up the unused door. Apart from dealing with the draught problem of an opening door once and for all, you may also find that you can gain extra usable space inside the house by eliminating the hall.

building-a-porch

Having removed the door, and its frame and sill, you will be left with a hole surrounded by bricks. You will have to obtain a brick to match that of the wall and here your builders’ merchant should be able to help if you take a brick along with you. If there are no old bricks around the building left over from other alterations such as a new window being fitted, you could remove a sample from the doorway when you have removed the door — you will in any case have to remove bricks in order to key in your new brickwork to the existing opening. Alternatively, and also if you fail to buy matching brick, find as good a match as possible and plan a concealing creeper or a bush where there used to be a door.

If your wall has a cavity the inner leaf can be of common brick or block to match the existing inner leaf. Knock out a brick either side every four courses, to provide a key (use a cold chisel and lump hammer to do this job), and start by building up your brick work from where the old sill rested to damp proof course level. This will be seen as a black line along the mortar joint about 150 or 225mm above ground level. If your house is old and has solid brick walls the

damp proof course may have been injected, in which case you will see a line of mortar-filled holes about the same distance above ground level. In the new brickwork put a length of black plastic damp proof course, either over the whole solid wall or on each leaf of the cavity wall, and bed it in mortar. Continue building up the brickwork above the damp proof course but, if you are forming a cavity, put a couple of butterfly type galvanised wall ties, one at either side of the opening, starting at the level of the damp proof course and then at 450mm intervals above this.

If you have gone to the trouble of having the cavity filled with foam then you will have to build insulation into your new cavity. Glass fibre

batts, sold for this purpose, are easy to use and should be supported off the wall ties at the level of the damp proof course so there is no chance of them becoming wet. Put the batts in place as the wall is built up.

A window can be built into the door opening with its head up against the lintel that was above the old door, with further lengths of damp proof course all round the window frame and behind the bricks that close off the cavity. The window should sit on the outer leaf of the cavity with a timber window board fixed over the cavity and the inner leaf on the inside. If you have chosen to brick up the front door you may have to find an alternative site for the letter-box. The new porch door would be the obvious place and our postman has been very understanding about the increased distance he has to walk round to the back of the house. Elsewhere we have seen bricked up front doors with the letter-box left in its old place and incorporated in the new brick wall.

If you do not go to the length of bricking up the front (or back) door, you may be able to put an extra door in your existing hall to create an airlock. This solution is often very easily adopted in a terraced house. The inner door need not be waterproof so you can buy an interior grade door and frame which will be cheaper than an external one. The new door should ideally be draught sealed along with the outer door. If the hall is wider than the door block the frame out with some lengths of 50mm x 100mm softwood or even with a short length of stud partition faced with plasterboard. When the airlock is complete just remember to shut one door before you open the other or the whole thing will be a waste of time. Perhaps it would help if you imagined you lived on board a starship!

If you have room for it outside the house, a fully enclosed porch makes a very good airlock, and a conservatory makes a very good porch, as well as being a source of solar heat. Off-the-peg conservatories are an excellent solution as these are cheap, reasonable in appearance and easy to erect. They usually sit on a simple brick or precast concrete base on very small foundations, so there is not a lot of digging and concreting to be done. Check with your local authority before you start designing a porch: it should not need planning permission but it will need to comply with the building regulations, and you may have to have proper foundations and so on. Given this fact it is probably worth building quite a large porch because it is hardly worth the trouble of digging the footings for a small one.

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